Added JPath expression operation

[mattnotmitt]

Should be able to close #96 with this.
Still todo:

• Add tests
• Figure out if a try-catch around jpath.filter() is required

[mattnotmitt]

Turns out there are better JSONPath implementations closer to the reference - hence I'm changing the library used to jsonpath.

[mattnotmitt]

I've now added tests and changed the library over - unfortunately, I can't use the npm package for jsonpath as it causes errors in webpack, which have been reported by other users. Instead I'm using a pre-packed file of the library which is the recommended fix by the author for this issue. Other users have found success by requiring it as a webpack external package but that wouldn't work for CyberChef's use case.

[n1474335]

Nice work. I've made a couple of slight changes, improving error messages with a bit more detail.

I found a fairly simple workaround for importing the jsonpath library which I've implemented. It's better to import our dependencies through npm if at all possible as it allows us to manage their updates in a more automated fashion.

Thanks for checking another operation off the list!

[mattnotmitt]

@n1474335 That is really weird - I was using that fix, but when building for tests, it wouldn't work at all! I wonder why it worked out for you...

[n1474335]

Not sure. I've recently updated some of the dependencies, including webpack itself, so that might be the difference.